Troubleshooting ESLint

Quick solutions to common ESLint problems, errors, and configuration issues.

Use Ctrl+F (or Cmd+F) to search for your specific error message on this page.

Installation Issues

Error: Cannot find module 'eslint'

Cause: ESLint is not installed or not in your PATH.Solution:

# Install ESLint locally
npm install eslint --save-dev

# Or globally (not recommended)
npm install -g eslint

# Verify installation
npx eslint --version

Always install ESLint as a dev dependency in your project, not globally. This ensures version consistency across your team.

Error: peer dependency warning for eslint

Cause: A plugin requires a different ESLint version than you have installed.Solution:

# Check ESLint version
npm list eslint

# Update ESLint to match plugin requirements
npm install eslint@^10.0.0 --save-dev

# Or update the plugin
npm install eslint-plugin-react@latest --save-dev

For pnpm users:

# Create .npmrc with:
auto-install-peers=true
node-linker=hoisted

Error: Cannot find module '@eslint/js'

Cause: The @eslint/js package is not installed.Solution:

npm install @eslint/js --save-dev

In your config:

import js from "@eslint/js";

export default [
  js.configs.recommended,
  // your config
];

Configuration Issues

Error: ESLint configuration not found

Cause: ESLint v10 cannot find eslint.config.js.Solutions:1. Create config file:

npm init @eslint/config@latest

2. Ensure correct filename:

✅ eslint.config.js
✅ eslint.config.mjs
✅ eslint.config.cjs
❌ .eslintrc (no longer supported in v10)
❌ .eslintrc.json (no longer supported in v10)

3. Verify file location:

# Config should be in project root or parent directories
ls -la eslint.config.js

4. Specify config explicitly:

npx eslint --config ./path/to/eslint.config.js .

Error: /* eslint-env */ comments are no longer supported

Cause: You’re using /* eslint-env */ comments, which are not supported in ESLint v10.Solution:Before (ESLint v8):

/* eslint-env node, es6 */
const fs = require('fs');

After (ESLint v10):

// Remove the comment from your file
const fs = require('fs');

In eslint.config.js:

import globals from "globals";

export default [
  {
    languageOptions: {
      globals: {
        ...globals.node,
        ...globals.es2021
      }
    }
  }
];

Error: Invalid configuration object

Cause: Your eslint.config.js has a syntax or structure error.Common mistakes:1. Not exporting an array:

// ❌ Wrong
export default {
  rules: { "no-console": "error" }
};

// ✅ Correct
export default [
  {
    rules: { "no-console": "error" }
  }
];

2. Mixing old and new config formats:

// ❌ Wrong (old format in flat config)
export default [
  {
    extends: ["eslint:recommended"] // No 'extends' in flat config
  }
];

// ✅ Correct
import js from "@eslint/js";
export default [
  js.configs.recommended
];

Debug your config:

node eslint.config.js

Rules not applying to my files

Cause: File patterns don’t match or files are ignored.Solutions:1. Check file patterns:

export default [
  {
    files: ["**/*.js", "**/*.jsx"], // Make sure this matches your files
    rules: {
      "no-console": "error"
    }
  }
];

2. Check ignored files:

export default [
  {
    ignores: ["dist/**", "build/**", "node_modules/**"]
  }
];

3. Debug config for a specific file:

npx eslint --print-config src/app.js

4. Verify file is being linted:

npx eslint src/app.js --debug

Error: Failed to load parser

Cause: Custom parser (like @typescript-eslint/parser) is not installed or configured incorrectly.Solution:1. Install parser:

npm install @typescript-eslint/parser --save-dev

2. Configure correctly:

import tsParser from "@typescript-eslint/parser";

export default [
  {
    files: ["**/*.ts"],
    languageOptions: {
      parser: tsParser, // Not as a string
      parserOptions: {
        project: "./tsconfig.json"
      }
    }
  }
];

Runtime Errors

Error: 'context.getFilename' is not a function

Cause: Using deprecated context methods removed in ESLint v10.Solution:Before:

module.exports = {
  create(context) {
    const filename = context.getFilename();
    const sourceCode = context.getSourceCode();
  }
};

After:

module.exports = {
  create(context) {
    const filename = context.filename;
    const sourceCode = context.sourceCode;
  }
};

Full migration table:

Removed	Replacement
`context.getCwd()`	`context.cwd`
`context.getFilename()`	`context.filename`
`context.getPhysicalFilename()`	`context.physicalFilename`
`context.getSourceCode()`	`context.sourceCode`

Error: Unexpected token 'export'

Cause: Your config file uses ESM syntax but Node.js is treating it as CommonJS.Solutions:1. Rename to .mjs:

mv eslint.config.js eslint.config.mjs

2. Add “type”: “module” to package.json:

{
  "type": "module"
}

3. Or use CommonJS:

// eslint.config.cjs
const js = require("@eslint/js");

module.exports = [
  js.configs.recommended
];

Error: Parsing error: Unexpected token

Cause: Parser cannot understand your code syntax.Solutions:For TypeScript:

npm install @typescript-eslint/parser --save-dev

import tsParser from "@typescript-eslint/parser";

export default [
  {
    files: ["**/*.ts", "**/*.tsx"],
    languageOptions: {
      parser: tsParser
    }
  }
];

For JSX:

export default [
  {
    files: ["**/*.jsx", "**/*.tsx"],
    languageOptions: {
      parserOptions: {
        ecmaFeatures: {
          jsx: true
        }
      }
    }
  }
];

For modern JavaScript:

export default [
  {
    languageOptions: {
      ecmaVersion: "latest",
      sourceType: "module"
    }
  }
];

Error: Failed to load plugin

Cause: Plugin not installed or imported incorrectly.Solution:1. Install plugin:

npm install eslint-plugin-react --save-dev

2. Import correctly:

import react from "eslint-plugin-react";

export default [
  {
    plugins: {
      react // Not as a string
    },
    rules: {
      "react/prop-types": "error"
    }
  }
];

Performance Issues

ESLint is very slow

Causes & Solutions:1. Enable caching:

npx eslint --cache .

2. Limit file scope:

export default [
  {
    files: ["src/**/*.js"],
    ignores: [
      "dist/**",
      "build/**",
      "node_modules/**",
      "**/*.min.js"
    ]
  }
];

3. Disable expensive rules:

export default [
  {
    rules: {
      // These require type checking (slow)
      "@typescript-eslint/no-floating-promises": "off",
      "@typescript-eslint/no-misused-promises": "off"
    }
  }
];

4. Use faster glob patterns:

# Slow
npx eslint "**/*.js"

# Faster
npx eslint src/

5. Parallelize in CI:

# Install
npm install eslint-parallel --save-dev

# Run
npx eslint-parallel 'src/**/*.js'

Out of memory errors

Cause: Large codebase or complex rules exceeding Node.js memory limit.Solutions:1. Increase Node.js memory:

NODE_OPTIONS="--max-old-space-size=4096" npx eslint .

2. Lint in batches:

npx eslint src/componentA/
npx eslint src/componentB/

3. Reduce file scope:

export default [
  {
    ignores: ["**/*.spec.js", "**/*.test.js"]
  }
];

Linting hangs or times out

Cause: Infinite loop in a rule or extremely complex file.Solutions:1. Identify problematic file:

npx eslint --debug . 2>&1 | grep "Linting"

2. Skip specific file:

export default [
  {
    ignores: ["src/problematic-file.js"]
  }
];

3. Update plugins:

npm update eslint-plugin-*

Editor Integration Issues

VS Code: ESLint not working

Solutions:1. Install ESLint extension:

Install “ESLint” by Microsoft from VS Code marketplace

2. Check output panel:

View → Output → Select “ESLint” from dropdown
Look for error messages

3. Restart ESLint server:

Cmd+Shift+P (Mac) or Ctrl+Shift+P (Windows/Linux)
Type “ESLint: Restart ESLint Server”

4. Configure settings.json:

{
  "eslint.experimental.useFlatConfig": true,
  "eslint.validate": [
    "javascript",
    "javascriptreact",
    "typescript",
    "typescriptreact"
  ]
}

5. Check workspace settings:

{
  "eslint.workingDirectories": [
    { "mode": "auto" }
  ]
}

WebStorm/IntelliJ: ESLint not working

Solutions:1. Enable ESLint:

Settings → Languages & Frameworks → JavaScript → Code Quality Tools → ESLint
Check “Automatic ESLint configuration”

2. Verify Node.js interpreter:

Settings → Languages & Frameworks → Node.js
Ensure correct Node.js version (20.19+)

3. Specify config file:

ESLint settings → Configuration file
Point to eslint.config.js

4. Clear caches:

File → Invalidate Caches / Restart

Conflicting Prettier/ESLint formatting

Cause: Both tools trying to format code differently.Solution:1. Use Prettier for formatting, ESLint for logic:

npm install prettier eslint-config-prettier --save-dev

2. Disable ESLint formatting rules:

import eslintConfigPrettier from "eslint-config-prettier";

export default [
  // Your config
  eslintConfigPrettier // Must be last
];

3. Run separately:

{
  "scripts": {
    "lint": "eslint .",
    "format": "prettier --write ."
  }
}

CI/CD Issues

ESLint passes locally but fails in CI

Causes & Solutions:1. Different Node.js versions:

# .github/workflows/lint.yml
- uses: actions/setup-node@v4
  with:
    node-version: '20.19' # Match your local version

2. Missing dependencies:

- run: npm ci # Use 'ci' not 'install'
- run: npm run lint

3. Cached node_modules:

- uses: actions/cache@v3
  with:
    path: ~/.npm
    key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}

4. Platform-specific line endings:

export default [
  {
    rules: {
      "linebreak-style": ["error", "unix"]
    }
  }
];

Exit code 0 even with errors

Cause: Errors are configured as warnings.Solutions:1. Use —max-warnings 0:

npx eslint --max-warnings 0 .

2. Change warnings to errors:

export default [
  {
    rules: {
      "no-console": "error" // not "warn"
    }
  }
];

Migration Issues

Upgrading from v9 to v10

See the complete Migration Guide for step-by-step instructions.Quick checklist:

✅ Node.js v20.19.0+
✅ Remove v10_config_lookup_from_file flag
✅ Remove .eslintrc files
✅ Remove /* eslint-env */ comments
✅ Update context methods in custom rules
✅ Update SourceCode methods

Converting .eslintrc to flat config

Old format (.eslintrc.json):

{
  "extends": ["eslint:recommended"],
  "env": { "node": true },
  "rules": { "no-console": "off" }
}

New format (eslint.config.js):

import js from "@eslint/js";
import globals from "globals";

export default [
  js.configs.recommended,
  {
    languageOptions: {
      globals: globals.node
    },
    rules: {
      "no-console": "off"
    }
  }
];

Use migration tool:

npx @eslint/migrate-config .eslintrc.json

Debugging Commands

npx eslint --print-config src/app.js

Getting Help

GitHub Discussions

Ask questions and get help from the community

Discord Server

Real-time chat with ESLint users and maintainers

Stack Overflow

Search existing questions or ask new ones

Report a Bug

File an issue on GitHub

Common Error Messages Reference

Quick reference for frequently encountered errors:

Error Message	Cause	Solution
`Configuration not found`	No `eslint.config.js`	Create config file
`Failed to load parser`	Parser not installed	`npm install parser`
`Failed to load plugin`	Plugin not installed	`npm install plugin`
`/* eslint-env */ not supported`	Using v8 syntax	Remove comment, use config
`context.getFilename is not a function`	Deprecated API	Use `context.filename`
`Invalid configuration object`	Syntax error in config	Check config syntax
`Unexpected token 'export'`	ESM/CJS mismatch	Rename to `.mjs` or add `"type": "module"`
`Parsing error`	Parser configuration issue	Configure correct parser

Still stuck? Include these details when asking for help:

ESLint version (npx eslint --version)
Node.js version (node --version)
Package manager (npm/pnpm/yarn)
Full error message
Relevant config file
Example code that triggers the issue

Get Started

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Guides

Troubleshooting ESLint

Troubleshooting ESLint

Installation Issues

Configuration Issues

Runtime Errors

Performance Issues

Editor Integration Issues

CI/CD Issues

Migration Issues

Debugging Commands

Getting Help

GitHub Discussions

Discord Server

Stack Overflow

Report a Bug

Common Error Messages Reference

Get Started

Using ESLint

Extending ESLint

Guides

​Troubleshooting ESLint

​Installation Issues

​Configuration Issues

​Runtime Errors

​Performance Issues

​Editor Integration Issues

​CI/CD Issues

​Migration Issues

​Debugging Commands

​Getting Help

GitHub Discussions

Discord Server

Stack Overflow

Report a Bug

​Common Error Messages Reference

Troubleshooting ESLint

Installation Issues

Configuration Issues

Runtime Errors

Performance Issues

Editor Integration Issues

CI/CD Issues

Migration Issues

Debugging Commands

Getting Help

Common Error Messages Reference